The invention relates to a system and method for securing a flexible marine riser to a floating structure.
Floating production systems are becoming more cost effective than fixed bottom-supported structures as oil and gas production operations progress into deeper waters. These floating production systems may consist of semi-submersible vessels, turret tankers, single-point mooring systems, tension leg platforms or any other type of floating structure. In a typical application of a floating production system, a number of underwater wells are connected to production equipment mounted on the floating structure via one or more flexible marine risers. Each flexible riser may comprise a flexible conduit such as a flowline or electrical cable, or a combination of multiple flowlines and electrical cables. The flexible risers may extend in a straight vertical direction from the water-bottom to the floating structure or have a catenary shape. At present there are two systems available for connecting a flexible marine riser to a floating structure.
In the first system, the riser is connected at its upper end to a riser receptor located at an underwater location near the bottom of the structure. As can be imagined, a problem exists of how to hook up a riser to a receptor at a submerged location since it requires utilization of remotely actuated pull-in equipment and/or the assistance of divers. In the other available riser connection system, the riser is connected to a receptor at the deck of the floating structure. In that case the flowlines and cable connections can be made in the dry, but the riser must pass through the splash-zone at the water surface and a large spacing is required between the riser and hull of the structure to avoid collision between the hull and riser in rough weather conditions.